In 1776, John Adams wrote that “equal interests among the people, should have equal interests in the representative body.” As fundamental a value as this is, it has proved quite difficult to preserve throughout our history.

Ever since the first federal election in 1788, when Patrick Henry persuaded the Virginia legislature to draw a house district unfavorable to a political enemy, James Madison, the nation has struggled with the evils of gerrymandering.

In 2010, California voters finally passed an initiative that created an independent redistricting commission to perform the decennial duty of making new congressional maps. It was given new criteria to use in drawing the lines that helped ensure that equality of interest.

Arizona also used the initiative process to create an independent redistricting commission. But the Arizona State Legislature is seeking to invalidate those 2011 congressional district lines, arguing that the U.S. Constitution mandates that only a legislature may perform that task. On Monday, the U.S. Supreme Court will hear arguments in the case.

Because this case directly affects California, we, along with three former governors of our state and the California Chamber of Commerce, filed an amicus brief in support of commissions.

A win for the Arizona Legislature could affect far more than merely the House maps in two states.

Should the high court issue a sweeping ruling endorsing the view that only a legislature can regulate elections, it would almost certainly invalidate the independent commissions now used in five other states and would call into question the “backup” commissions and advisory commissions used in seven other states.

It might also foreclose the scenario that happened in California in 1991, where the Legislature and governor deadlocked, and the state Supreme Court intervened. Most people believe the districts produced by the court’s experts were the fairest and most competitive in state history.

And it might have effects far beyond redistricting by casting doubt upon the validity of many types of reforms now considered fundamental parts of the right to vote.

There is a lengthy list of innovations and policies that were originally enacted in individual states by a vote of the people. These include substantive ideas such as the switch from voting for a party slate to choosing individual candidates, the consolidation of state and federal elections, and the direct presidential primary. Also included are modernization measures such as changing the form of the ballot and allowing voting machines. Even present day changes to election rules, such as Mississippi’s recent adoption of a voter ID law, would be open to challenge. The people would no longer have the authority to act.

At its core, this case rests on the Supreme Court’s interpretation of the Elections Clause of the U.S. Constitution, which states: “The times, places and manner of holding elections for senators and representatives, shall be prescribed in each state by the legislature thereof; but the Congress may at any time by law make or alter such regulations.”

The Arizona Legislature argues that the word “legislature” must mean the members of its two chambers voting as a body. But the dictionaries of the era defined legislature as “the power that makes laws.” Hence the case will likely turn on the Supreme Court’s conclusion about the intent of the Framers in 1787 and on how political thinking in that remarkable era conceptualized the structure of government.

The ratification debates focused intensely on federalism, the power relationship between the existing state and nascent national governments. It is true the Framers were distrustful of “mob” rule. Only the U.S. House was directly elected; the president and Senate were chosen by electors and state legislators, respectively. But the Framers were also deeply distrustful of state legislatures, fearing that the states could cripple the new government by refusing to provide for federal elections, and so gave the Congress power to override any regulations a state legislature might enact. The Framers’ commitment to checks and balances makes it less likely they would have rejected the right of the people to use initiative and referendum as a brake on the authority of a legislature.

Until now, initiative and referendum have had an influence on the regulation of elections even when left unused. The threat of a ballot measure often provides the impetus for legislatures to enact reforms they can accept rather than risk the imposition of ones they cannot. Absent that, in states with initiative and referendum, the odds of legislative action will decline.

The Supreme Court could potentially undo much of what California voters have recently enacted. Even a partial victory by the Arizona Legislature could open the door to a reversal of decades of hard-won progress in election reform. The tools of popular sovereignty should be jealously safeguarded if equal representation is to be preserved.

Bill Mundell is the former chairman of Californians for Fair Redistricting and was the executive producer of the 2010 feature documentary “Gerrymandering.”

Charles T. Munger Jr. is a physicist and the proponent and chief backer for California’s Proposition 20, which gave the California redistricting commission authority to draw California’s 53 congressional districts.

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